IEEE (Institute of Electrical and Electronics Engineers) 802.16 standards provide techniques and protocols to support a broadband wireless access. Standardization proceeded starting from 1999 and IEEE 802.16-2001 was approved in 2001. It is based on a single carrier physical layer called ‘WirelessMAN-SC’. Later, besides the ‘WirelessMAN-SC’, ‘WirelessMAN-OFDM’ and ‘WirelessMAN-OFDMA’ were added to the physical layer in IEEE 802.16a standards approved in 2003. After the IEEE 802.16a standards were completed, revised IEEE 802.16-2004 standards were approved in 2004. IEEE 802.16-2004/Cor1 (referred to as ‘IEEE 802.16e’, hereinafter) was completed in the form of corrigendum in 2005 in order to resolve and correct bugs and errors of the IEEE 802.16-2004 standards.
In general, Multicast and Broadcast Service (MBS) is used in a single frequency network (SFN) to obtain a frequency diversity gain and a macro diversity gain. A plurality of base stations transmit the same MBS signals employing the same Modulation and Coding scheme (MCS), permutation, or the like, to user equipments (UEs). The same MBS signals transmitted from multi-cell do not act as inter-cell interference but act as self-signals to bring about an effect such as multi-path fading. The UEs can obtain an SFN gain such as frequency diversity, macro-diversity, or the like, from the same MBS signals transmitted from the multi-cell.
A delay spread with respect to the MBS signals transmitted from the multi-cell may be considerably increased according to the distance between the base stations and the UEs, compared with a general unicast signal. If the delay spread of the MBS signals is increased to exceed a cyclic prefix (CP), an inter-symbol interference (ISI) is generated. The CP is an interval where no signal is carried to prevent the ISI. Thus, the length of the CP with respect to the MBS signals should be longer than the unicast signal. However, the increase in the length of the CP in the limited radio resources would relatively reduce a resource domain that can carry data. If the inter-site distance (ISD) is long, the delay spread with respect to the MBS signals would be increased, so, preferably, the length of the CP is increased, while if the ISD is short, the length of the CP is preferably reduced.
However, a frame that may accept such CPs having various lengths and being possibly applicable to the MBS signals has not been explicitly presented yet.